Input: applespi - use guard notation when acquiring spinlock
This makes the code more compact and error handling more robust
by ensuring that locks are released in all code paths when control
leaves critical section.
Link: https://lore.kernel.org/r/20240825051627.2848495-3-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>